Optical Cable: Is it okay if it's coiled?

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pr0m3th3u5

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Location
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ISP
BSNL
Just a BSNL Fiber connection. The black thick optical cable is coiled into a circle, before it's connected to a white box, quite a few times by the BSNL guy. Then there is this thin yellow wire from the white box to the modem (what is it called?) it is also bent at 90 deg at a couple of places... Is it okay? I remember reading in a school textbook that optical fiber cable shouldn't be bent, IIRC at 90 deg angles. Will this effect speed?

The thing is I have a 200Mbps connection but barely get 100Mbps...

I am wondering what could be the issue here...
 
The black outdoor cable should be fine coiled.

The thin indoor cable is more sensitive and sharp bends will result in lower power reaching ONU.

You should open ONU interface and check the PON Information.
 
@pr0m3th3u5 make sure the coils are larger than 10 cm or 4" in diameter. Do not coil optical fibres tightly and never bend them at an acute angle.

You can check on your ONT's optical PON information if signal strength is affected by the coils.
 
Is it the transmission power that is relevant? Are these values good enough?

Vendor NameAlphion
Temperature47.742188 C
Voltage3.268200 V
Tx Power2.359838 dBm
Rx Power-22.441251 dBm
Bias Current22.150000 mA
 
My BSNL connection has the same setup. That thick black cable is the outdoor cable and is relatively durable and resistant to physical stresses while the yellow one is an optical patch cord. The yellow patch cord is comparatively sensitive to sharp angles and coiling in tight loops. That said, to be on the safe side just make sure all opt. cables treated gently. Cables have nylon strand reinforcements inside but the fibre strand itself is brittle.
 
I got rid of severe bends as advised. The values very slightly improved (100ths).

But the low speed still exits... You said the PON values are pretty good so what cloud be the problem?

During the installation day the speed showed 200 Mbps but not since... The ridiculous thing is on PC which is connected to the router using 100 Mbps LAN the speed is consistently shown as ~90 Mbps (~80 Mbps before correcting those bends) whereas on Mobile with 5Ghz (433 Mbps) (less then 1 meter from wifi modem) the speed is consistently shows as 50Mbps... I did change the LAN cable that connects modem to PC... maybe the gain in speed is explained by that...


Is it possible I messed with modem settings (I did mess with some stuff... ) that affected the speed?
 
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